This invention relates to a closure for a cable connection adapted to be arranged in a hand hole, a shallow access hole of a smaller size (a so-called fingerhole) or the like, and more particularly to a closure suitable for connection of optical fiber cables including optical fibers and tension members to fiber connection sections or for branch connection of optical fiber cables. In particular, the present invention is concerned with a closure for a cable connection which is adapted to receive fiber connection sections of optical fiber cables in a casing body of the closure while securely holding the optical fiber cables including tension members therein and facilitate access to the fiber connection sections.
In general, connection between cables such as optical fiber cables is carried out by connecting or splicing optical fibers of the cables to each other by means of connectors and protecting the connectors in a closure. Such a closure, particularly, a closure for connection of underground cables is required to meet requirements contrary to each other. More particularly, the closure is required to exhibit fluid tightness or sealing characteristics sufficient to prevent intrusion of water or the like into the closure and facilitate access to fiber connection sections of cables. Thus, a conventional closure for a cable connection, in order to ensure both satisfactory sealing characteristics and connection workability, employs either a casing structure constructed of two casing halves joined to each other through a seal member by means of screws or a casing structure wherein a casing is formed with an opening for access to the fiber connection sections and the opening is closed with a lid through a seal member by means of screws.
Unfortunately, the conventional closure renders connection between short excess fibers in a hand hole or the like troublesome when branch or drop connection between optical fiber cables previously laid is required, resulting in being obliged to employ an intermediate post-branch procedure wherein after cutting of all fibers of a cable, required branch and drop cables are connected and taken out and the remaining fibers are re-connected. Unfortunately, this needs management for identification of the fibers and an additional connection operation. Also, access to the fiber connection sections requires troublesome removal and remounting of tension members. Further, branch and lead-in connection of optical fiber cables and maintaining of the branch and lead-in connection at increased reliability necessarily require both repeating of the connection and repairing of the branch and lead-in connection. Furthermore, the conventional closure renders sealing of the closure against an ambient environment troublesome and renders both replacement and increase of the fibers difficult. In addition, in order to ensure safety of fiber connection sections and improved workability for cables of different diameters, the conventional closure is complicated in structure and increased in cost. In particular, the conventional closure fails to be commonly applied to various connection procedures such as a full-fiber connection procedure, an post-branch connection procedure, a conversion fiber connection procedure and a drop cable connection procedure and the like. Moreover, the conventional closure, when it is arranged in a hand hole or a so-called finger-hole, deteriorates workability in a cable connection operation because it needs tools for connection.